1. Field of the Invention
The present invention relates to a lock device that locks and unlocks a lock mechanism or the like by manipulation of a key inserted into a key insertion hole.
2. Description of the Related Art
A lock device disposed in a door of an automobile or the like is, for example, disposed with a cylindrical case member, a sleeve member that is rotatably disposed inside the case member, a plunger member that is rotatably disposed inside the sleeve member, a rear rotor that is rotatably disposed so as to face the plunger member in an axial direction, and a lock lever that is disposed so as to rotate integrally with the rear rotor (e.g., see Japanese Patent Application Publication (JP-A) No. 8-4387).
This lock device is configured such that, when a regular key is inserted into a key hole, the plunger member releases the state of engagement between the plunger member and the sleeve member, just the plunger member becomes rotatable, and the plunger member can cause the rear rotor to rotate. Thus, the lock lever rotates together with the rear rotor, and a lock mechanism in a door of a vehicle or the like is unlocked by the manipulating force of the lock lever.
Further, when a key substitute, such as a key whose shape is different from that of the regular key or a driver (these will generically be called an “irregular key” below), is inserted into the key hole in the plunger member and forcibly rotated, tumbler members maintain the state of engagement between the plunger member and the sleeve member, and the plunger member and the sleeve member integrally rotate, so the plunger member cannot cause the rear rotor to rotate.
In other words, the lock device is configured such that the plunger member and the sleeve member integrally rotate even when an irregular key that has been inserted into the plunger member is rotated, but the rear rotor and the lock lever cannot be caused to rotate, and the lock mechanism is not unlocked.
That is, in the lock device described in JP-A No. 8-4387, when the regular key is inserted into the key hole and the plunger member is caused to rotate, the lock mechanism can be unlocked, but when the irregular key is inserted into the key hole and the irregular key is forcibly rotated, the plunger member and the sleeve member rotate together, so the lock mechanism is not unlocked. Moreover, because the plunger member and the sleeve member rotate together, unreasonable force does not act on the tumbler members that engage the plunger member and the sleeve member, so the lock device is structured such that damage to the tumbler members and the like is prevented.
However, when the lock device is to be unlocked, a plate-shaped key must be inserted into the key hole in the lock device and rotated counter to the rotational resistance of the plunger member, the rear rotor and the lock lever and the actuated resistance of the lock mechanism.
For this reason, in regard to the key used in this lock device, the material thereof is limited to a high-strength material such as iron or stainless steel, and it is necessary to make the thickness of the key sufficiently thick in accordance with the size of the transfer torque.
Further, in this lock device, plural plate-shaped tumbler members arranged in the plunger member are disposed at predetermined intervals in the axial direction and so as to be movable in an axis-orthogonal direction. When a key is inserted into the key hole, the concavo-tongue portions of the key and the key insertion hole in the plunger member contact each other. In the case of the regular key, all of the tumbler members move to regular positions and just the plunger member rotates, but in the case of the irregular key, at least one of the tumbler members moves to an irregular position, the plunger member and the sleeve member integrally rotate, and the rear rotor cannot be caused to rotate.
On the other hand, it is necessary to increase the number of the tumbler members in order to diversify the types of keys, and there is also the problem that the axial direction length of the plunger member must be made longer when the number of the tumbler members disposed at predetermined intervals in the plunger member is increased.